This invention relates to mixtures of fluorinated hydrocarbons and more specifically to substantially constant boiling mixtures of octafluoropropane (FC-218) and fluoroethane (HFC-161).
Recently the long-term environmental effects of chlorofluorocarbons have come under scientific scrutiny, because it has been postulated that these materials because of their high stability are able to reach the stratosphere where under the influence of ultraviolet radiation release chlorine atoms which, in turn, undergo chemical reaction with stratospheric ozone. Reduction of stratospheric ozone would increase the amount of ultraviolet radiation reaching the earth's surface. In view of the potential environmental problems associated with stratospheric ozone depletion, there is a need for new materials possessing properties which make them useful substitutes for applications in which chlorofluorocarbons have been used and are environmentally safe.
There is a limit to the number of single fluorinated hydrocarbon substances which could be candidates as environmentally safe materials. Mixtures of known fluorinated hydrocarbons, however, might be used if the desired combination of properties could be found in a given mixture. Simple mixtures, however, create problems in design and operation of refrigeration and other equipment because of component segregation in both the vapor and liquid phases. To avoid component segregation problems, it is particularly desirable to discover new azeotropic or substantially constant boiling fluorocarbon blends. Such blends or compositions should not suffer from component segregation problems. Unfortunately, it is not possible to predict the formation of azeotropes or substantially constant boiling compositions, thus complicating the search for novel azeotropic compositions which possess the desired combination of properties.
There is a need for substantially constant boiling compositions which have properties which make them particularly useful as refrigerants, aerosol propellants, heat transfer media, gaseous dielectrics, fire extinguishing agents, expansion agents for polyolefins and polyurethanes and as power cycle working fluids and that are potentially environmentally safe.